1 Place the four, sugar and butter in a bowl and place in the freezer for 15 minutes. Rub the butter into the flour until the mixture resembles breadcrumbs, or blend in a food processor.
2 Add the egg yolk, vanilla extract and enough ice cold water to form a dough. Press the dough into a flat disc, wrap in clingfilm and chill in the fridge for 30 minutes.
3 Heat the oven to 200ºC (180º fan) 400ºF, gas 6. Mix the rhubarb and strawberries together and place in a pie dish. Sprinkle over the sugar and orange juice.
4 Roll the pastry out and cut a circle to make the pie lid. Place on top of the pie, moistening the edge top make a good seal, and decorate with pastry offcuts. Brush with the beaten egg and bake for 30 - 40 minutes or until the pie is golden brown.